Implement 2 versions of binary search in binarySearchArray.js

binarySearchArray/binarySearchArray.js

@@ -13,5 +13,65 @@ exhibits the desired characteristics.
 **/
 
 var binarySearch = function (array, element) {
-
+  var length, mid, midValue, left, right, result;
+
+  // check for allowable conditions
+  if ( Array.isArray(array) && typeof element === 'number' ) {
+    length   = array.length;
+    mid      = Math.floor( length / 2 );
+    midValue = array[mid];
+    left     = array.slice(0, mid);
+    right    = array.slice(mid + 1);
+    result   = 0;
+
+    if (length === 0) {
+      // base condition
+      return null;
+      // result = null;
+    } else if ( midValue === element ) {
+      return mid;
+      // result = mid;
+    } else if ( midValue > element ) {
+      return binarySearch( left, element );
+      // result = binarySearch( left, element );
+    } else {
+      var temp = binarySearch( right, element );
+      // result = temp === null ? temp : mid + temp + 1;
+      return temp === null ? temp : mid + temp + 1;
+    }
+    // return result;
+  }
+};
+
+
+// Space Complexity O(log n) b/c of recursive stack
+var binarySearch = function (array, element) {
+  var inner = function (lowerBound, upperBound) {
+    var mid      = Math.floor( (lowerBound + upperBound) / 2 );
+    var midValue = array[mid];
+
+    /*
+     * base condition: if the mid index is either of the bounds,
+     * then if neither of the array values at the index doesn't
+     * equal the value, then the value can't be found in the array
+    */
+    if ( mid === lowerBound || mid === upperBound ) {
+      return midValue === element ? mid : null;
+    } else if (midValue === element) {
+      return mid;
+    } else if (midValue > element) {
+      return inner(lowerBound, mid);
+    } else {
+      return inner(mid, upperBound);
+    }
+  };
+
+  // check for allowable conditions
+  if ( !Array.isArray(array) ) {
+    throw new Error('Need to pass in a valid Array object');
+  } else if ( typeof element !== 'number' ) {
+    throw new Error('Need to pass in a valid Number to find in Array');
+  } else {
+    return inner(0, array.length);
+  }
 };